I have to agree with Robert. The best connection is always going to be a correctly made and soldered joint. Crimps, screw down connector blocks or just twisting wires are all likely to be sources of trouble in the future.
On a medium to largish layout I would recommend nothing smaller than a conductor size of 2.5mm and an even larger size if the layout is more than 4 plus mtrs long. I used some twin & earth (T & E) 2.5mm cable removing the outer sheathing and then laying the two insulated conductors around the layout and stripping back a short length of the insulation wherever I need to make a soldered connection to any droppers or other accessories etc. As a bonus, I also ran the 1.5mm bare former earth wire for the T & E cable around the layout as this is my common return conductor for everything that's not DCC
A couple of pictures and further explanation are on my site DCC Wiring
BTW...Dynamite26, your link to Rapid fails to specify which of the five sizes of conductor you're using as a power bus?
On a medium to largish layout I would recommend nothing smaller than a conductor size of 2.5mm and an even larger size if the layout is more than 4 plus mtrs long. I used some twin & earth (T & E) 2.5mm cable removing the outer sheathing and then laying the two insulated conductors around the layout and stripping back a short length of the insulation wherever I need to make a soldered connection to any droppers or other accessories etc. As a bonus, I also ran the 1.5mm bare former earth wire for the T & E cable around the layout as this is my common return conductor for everything that's not DCC

A couple of pictures and further explanation are on my site DCC Wiring
BTW...Dynamite26, your link to Rapid fails to specify which of the five sizes of conductor you're using as a power bus?

